[Gary Huff]"Exactly how? What will FCPX be optimized for on the Mac Pro that it currently doesn't support on a high-end iMac? Outside of dual GPU, which I assume would be included as part of the OpenCL framework anyway."

OpenCL certainly lets you use two GPUs, but I don't think this is entirely automatic — you'd have to set up a second dispatch queue, at least. And OpenCL supports reserving portions of GPUs for its own use, which you'd probably want to do differently on a dual GPU system. So there's that.

Apple's wording also almost makes wonder if maybe the HDMI port on the machine can actually be used directly for broadcast monitoring, and FCP is adding support for that. (Though I'd consider this a bit unlikely.)